movement/registration/perforations??????

Ive been reading up on the Kodak products guide. I noticed that 16 mm color neg films have both one edge and two edge perforations. 35 mm does not.What is the difference?
How does this relate to 4 perf and 3 perf? Ive read on arri.com that 3 perf is more economical.

What does the movement of a camera have to do with all this? From what ive read in the ac manual, all the 35 mm cameras are dual registration. The only difference is in the pull down claws ( 1, 2 or 3). what about 16mm?
How do i change from 3 perf to 4 perf in camera?

trying to make sense of this....Hope the questions have been put forward properly...

35mm film always has perfs running down both sides so there is no reason to label it as double-perf.

Super-16 uses single-perf film stock, and most 16mm cameras can use single-perf stock too, so Kodak mainly sells single-perf in 16mm and if you need double-perf stock, then it's usually a special order item.

Standard 35mm has a 4-perf pulldown, especially for print projection, but you can shoot using a shorter 3-perf (or even 2-perf) negative frame and convert it in post by transferring it to 4-perf 35mm film for printing/projection (usually a D.I. is required.) If you are shooting 35mm for transfer to TV, then 3-perf saves you 25% over 4-perf, being one perf shorter, but if you are shooting for theatrical release, you have to factor in the extra conversion costs to create a 4-perf printing negative from a 3-perf original.

4-perf 35mm Full Aperture (the whole usable negative from side to side and top to bottom) is 1.33 : 1 (4x3) whereas the shorter 3-perf frame is 1.78 : 1 (16x9) in shape.

You need to use a camera with a 3-perf pulldown movement if you want to shoot 3-perf. It is not a simple conversion usually and there are not 3-perf movements even made for all types of 35mm cameras. It's not something you can easily switch yourself back and forth to, from 4-perf to 3-perf and back. Generally you would decide what format to have your camera permanently converted to, if even possible or affordable.

Registration is different than pulldown, though some cameras sort of combine the two funtions. 16mm cameras use a variety of methods to get good registration, whether or not they use a registration pin. Of course, some have mediocre registration, which isn't always a horrible thing unless you will be compositing over the image in post.

I could write a big description of how it all works - but rather than do that I suggest grabbing a camera and/or piece of film from both formats and having a look at it - think about it for a while and most of the answers will come to you - the rest can be answered with a search here or at wikipedia etc...